Snap action switch



Oct. 27, 1970 ISAO NISHIMURA SNAP ACTION SWITCH Filed Jan. 4, 1968 United States Patent 3,536,871 SNAP ACTION SWITCH Isao'Nishimura, Kyoto, Japan, assignor to Tateisi Electronics Co., Kyoto, Japan Filed Jan. 4, 1968, Ser. No. 695,715 Claims priority, application Japan, Jan. 14, 1967,

Int. Cl. H6111 13/36 US. Cl. 20067 1 Claim ABSTRACT OF THE DISCLOSURE A snap action switch comprises an actuating member engaged with a common terminal member, a first member and a second member. One end of the first member is engaged with the actuating member and the other end has a movable contact facing stationary contacts. The second member is engaged with the first member at one end and the other end is engaged with the common terminal member. During the downward pivotal movement of the actuating member, an intermediately located bending portion in the first member reverses pressure, by which snap switching action is effected.

The present invention relates to improvements in switches, more particularly, in switches having snap acting mechanisms.

At present numerous switches having snap acting mechanisms are offered for use. For instance, United States Letters Patent No. 2,513,804 issued on July 4, 1950 provides a switch which is now extensively used as a useful and effective device. In such a switch, however, the members corresponding to a first member acting as a tension element and to a second member serving as a compression element in a switch of the present invention to be hereinafter described are joined together in a position near to the contacting portions of the movable contract and stationary contacts, so that the second member is influenced by he are heat of several hundred degrees centigrade generated upon contact of both of the contact points with the result that the material of the second member is caused to change in its properties, which reduces the deterioration of the resiliency thereof, for instance, thereby taking place. The characteristic performance and service life of the switch are therefore subjected to extremely objectionable resultsthus produced. In addition, since the above-mentioned first and second members in the conventional switch are integrally formed of one element, such forces as bending, tensile, distorting compressive forces and the like are in complicated manner applied on the diverging portion of the first and second members during the switching operation, thereby further creating inscrutable stress at the portion. This stress, as a result, tends to cause breakage in said portion or impair the snap action of the switching mechanism,

and furthermore, such substantial defect of the conventional switch is made more serious by the are heat.

A principal object of the present invention is accordingly to provide a novel snap action switch which is useful and practical and in which careful consideration it given to the above described problems.

In more detailed description, a principal object of the present invention is to provide a snap action switch in which, whereas the snap acting mechanism therein comprises a combination of two members, namely, of a first member acting as a tension element and a second member acting as a compression element, said members are protected against unfavourable influence to be exerted upon contacting of the contacts by the aforementioned are heat of several hundred degrees centigrade, and the 3,536,871 Patented Oct. 27, 1970 maintenance of high switching performance is thereby secured.

Still another object of the present invention is to provide a novel snap action switch in which objectionable influence to be exercised upon switching operation as aforementioned is eliminated by a snap acting mechanism comprising a combination of respectively independent two members and which as thereby provided with enhanced stability of characteristics of switching performance and improved snap action as well as high resistance against vibration and shock impact.

Other objects and advantages of the present invention will become apparent from the following detailed description with reference to the accompanying drawings, in which:

FIG. 1 is a front elevation in cross section showing a snap action switch in accordance with the present invention;

FIG. 2 is a front elevation of a snap action switch in accordance with the present invention, the cover plate being removed to show the operation; and

FIG. 3 is a view in perspective showing a first member and second member of a snap action switch in accordance with the present invention, the parts being disassembled.

Now referring to FIG. 1, there is shown a common terminal member 2 disposed in a switch case 1 with one end thereof outwardly extending from the case. Pivotally engaged with the common terminal member 2 at an engaging point A is one end of an actuating member 3 and the other end thereof is adapted to receive the pres sure from a push button 4. A first member 5 made of a resilient material and disposed approximately horizontally within the case 1 has one end engaged with said actuating member 3 at a point B so as to move relatedly therewith, the other end thereof being left unsupported and provided with a movable contact 8 facing stationary contacts 6 and 7. A bending portion 5A for reserving pressure for reversing switching action is formed in an intermediate portion in the first member 5, preferably in a position as far from the movable contact 8 as permissible.

A second member 9 is formed of a rigid and yet nonresilient material such as brass or the like, and one end thereof is interrelatedly engaged with said first member 5 at a point C, the other end being pivotally engaged with the common terminal member 2 at a point D. By interrelated engagement herein used is meant a manner of engagement in which separate two members are interlocked together so as to operate relatedly with respect to the structure. It does not therefore embrace joining the first and second member into a unitary and inseparable piece as by welding, bonding, riveting or the like. As an example of interrelated engagement, FIG. 3 illustrates an embodiment in which the first member and second member are joined together with a groove 10 formed in a surface at one end of the second member being engaged with an edge 12 of the rectangular opening formed in the first member. However, it is by no means limited only to such an embodiment.

Now, in FIG. 1, when the push button 4 is pushed down, the depressing pressure is delivered to the actuating member 3, and supported at an engaging point A, it is urged to pivotally move downward. Due to this pivotal movement of the actuating member 3, the engaging point B joining the first member 5 and the actuating member 3 is brought down with a circular arc movement with a resultant tension created to the first member 5. Since the first member 5 is at the point C engaged with the second member 9 which is, supported at the engaging point D, moved pivotally, the first member 5 is subject to tension which works thereon in the directions toward its ends. The tension exerted on the bending portion 5A serves to stretch this portion. In the present embodiment, the radius of the pivotal movement of the second member from the supporting point D to the engaging point C is so adapted to be slightly larger than the radius of the pivotal movement of the actuating member from the supporting point A to the engaging point B. Therefore, when the above-mentioned tension is created in the first member, the first member moves toward the rightward direction in the figure by a distance of the difference between said two radii, whereby Wiping action is effected on the stationary contact by the movable contact 8 mounted on the one end of the first member, protecting the actuating portions against the damage to be produced by the are heat upon switching. In this condition the actuat ing member 3 keeps moving pivotally to urge the engaging point B joining the actuating member 3 and the first member 5 to move beyond a dead line, namely, beyond a line connecting the engaging point D joining the common terminal member 2 with the second member 9 and the engaging point C joining the second member 9 with the first member 5, whereupon the reversal force reserved by the aforementioned stretch of the bending portion 5A of the first member 5 works instantaneously to bring the movable contact 8 on the first member into contact with the other stationary contact 7 in a quick switching action as shown in FIG. 2.

As apparent from the above-described structure, the present invention comprises the second member 9 acting as a compression element and formed of a nonresilient rigid material and the first member acting as a tension element, said second member being engaged with the first member, so that the second member, even when it is engaged to the first member in a position proximate to the contacting portions, is free from disadvantageous effects to be exercised by the are heat, While the bending portion 5A to be formed in the first member can be disposed in a position far from the contacting portions to thereby protect the bending portion against objectionable effects of heat. Thus, through eliminating the damage attributable to the arc discharge such as unstable switching action, abbreviation of the service life or the like, excellent switching performance is insuring over a long period.

Furthermore, it will readily be understood that since the present invention comprises the first member and second member which are each separately formed and thereafter engaged with each other so as to interrelatedly operate, the position of the dead line can be more definitely determined than in a switch of conventional type. In the conventional switch, as already described in detail, a portion of the first member acting as a tension element was diverged to form the second member integrally therewith. Upon switching operation, therefore, tensile, compressive, stretching, bending, distorting forces and the like were in complicated and interrelated manner exerted between the two members, particularly in the diverging portion and inscrutable stress was consequently created in said portion. As a result, the conventional switch was subject to such defects that the position of the dead line could not be defined, the characteristic performance of switching action was unstable, snap action was deteriorated, or the diverging portion was broken, and in addition, such defects were made more serious by the effects of arc heat.

However, by providing a structure which is free from the influence of are heat, the present invention has precluded the generation of the above described inscrutable stress, facilitating to clearly define the position of the dead line and effecting stable switching operation and improved snap action. Also because the incrutable stress has been precluded, the pressure to be applied on the push button 4, be it ever so small, can precisely be sensed for reliable switching operation; a high precision switch has thus been made obtainable.

Although the present invention has been described with respect to a typical embodiment, the inventor does not wish to limit the invention only to the embodiment, but it is to be understood that the invention may also reside in the alterations, modifications and equivalents without I departing from the principle of the present invention and the spirit of the inventor as set forth in the claim stated hereinafter.

What I claim is:

1. A snap action switch comprising a casing, a push button slidably mounted in the casing, a common terminal member mounted in the casing, a pair of spaced-apart stationary contacts mounted in the casing, an elongated actuating member having one end pivotally engaged with the common terminal member and the other end engageable with the push button, an elongated first member made of resilient material having one end engaged with'the actuating member for movement therewith and the other end extending between the stationary contacts and carrying a contact member, the first member having a generally U-shaped bending portion intermediate the ends thereof and spaced from the stationary contacts, a generally L-shaped second member formed separately from the first member and formed of relatively non-resilient rigid material having one end pivotally engaged with the common terminal and the other end pivotally engaged with the common terminal and the other end engaging the first member for movement therewith, the distance between the point of pivotal engagement of the second member with the common terminal and the point of engagement of the second member with the first member being slightly greater than the distance between the point of pivotal engagement of the actuating member with the common terminal and the point of engagement of the actuating member with the first member whereby the U-shaped bending portion of the first member is stretched by the second member as the actuating member pivots about the common terminal to provide wiping action between the contact member carried by the first member and one of the stationary contacts.

References Cited UNITED STATES PATENTS 1,960,020 3/1934 McGall. 2,387,089 10/1945 Peterson et a1.

3,291,930 12/1966 Hippie.

ROBERT K. SCHAEFER, Primary Examiner D. SMITH, JR., Assistant Examiner 

